Airfoils used in aircraft engines, such as fan blades of a gas turbine engine, can be susceptible to extreme loading events. For instance, a fan blade might strike a bird that is ingested into the engine, or a blade-out occurrence may arise wherein one of the fan blades is severed from a rotor disk. If the impact is large enough, a fan blade may break apart into one or more shards before traveling downstream through the engine. Larger shards may cause undesirable damage to the aircraft or engine. Some airfoils are formed with various features to increase overall airfoil strength or rigidity. Nonetheless, it is difficult to prevent all breaks from occurring. Moreover, such features may cause an airfoil to only partially break during certain loading events. If the break is not complete or clean, greater damage may occur as the partially severed blade gains energy from the engine's rotation. In some instances, the airfoil shards may be projected through the engine and to the aircraft or surrounding environment.
In addition to concerns over the size and speed at which an airfoil breaks, the shape of an airfoil's broken shards may dictate the damage caused by an extreme loading event. Knowing the likely size and shape of an airfoil's fragmented pieces may allow better predictions and preparation for such occurrences. Fragments having an unanticipated shape or size may cause greater level of damage to the engine. However, minimizing or modeling the size of an airfoil's fragments can be difficult. In existing airfoils, the location and size of an airfoil break will vary greatly depending on the magnitude and location of an extreme loading event. Predetermining or shaping the fragmented pieces in advance may allow users to minimize and predict the detrimental effects of an airfoil break.
Accordingly, further improvements are desired to aircraft airfoil structures. For instance, it may be desirable to control the impact or break behavior of an aircraft engine airfoil.